Bill asks<<
Do you know if the SN1987A rings, which became visible about a year
after the explosion, are now brighter, the same, or dimmer than they
were in 1988?>>
Dimmer it appears:
"The near-perfect image correction now delivered by the COSTAR optics (Jedrzejewski et al. 1994)
has again made SN 1987A and its surroundings easily observable with HST-in spite of the object now being nearly an order of magnitude fainter than when it was first observed with the FOC in 1990 August. "
http://www.aas.org/Epubs/eapjl/v435/jakobsen/orig/jakobsen.html